In January 2021, the National Institute of Industrial Property (INPI, i.e. the French Patent Office) published its comprehensive guidelines on the patent opposition procedure. These guidelines are the last stone of a legal edifice, the construction of which began with article 121 of the PACTE law of May 22, 2019. As a consequence, it is now possible to have a clear view of the procedure. To mark this occasion, we are publishing a series of five articles throughout which we strive to establish an overview of the main aspects of the opposition procedure, including the issues that remain unresolved. This first article of the series provides an introduction and general overview of the opposition procedure.

Against which IP right?

Any French patent having a mention of grant published since April 1, 2020 by the National Institute of Industrial Property (INPI) may be subject to opposition (L.613-23 of the Intellectual Property Code).

The opposition procedure cannot be applied to utility certificates or supplementary protection certificates. The utility certificate has recently grown into a real tool for obtaining a simplified grant as compared to a patent, which guarantees IP quality due to its reinforced examination and the possibility for opposition.


The opposition must be filed within 9 months from the publication of the mention of the grant (R.613-44 CPI).

This time limit cannot be extended and is not subject to reestablishment of rights. Therefore, it is essential to monitor the grant of French patents against which it may be desirable to file an opposition. 

Opposition by whom?

Any natural or legal person may file an opposition except the patent owner (L.613-23 CPI).

There is no need to demonstrate standing (i.e., interest in the matter) (Guidelines B, 1.2.). This should allow opposition to be filed via a nominee, or a straw man.

What ground(s) and scope?

The grounds for opposition are limited to (L.613-23-1 CPI):

  • lack of novelty, inventive step and/or industrial application,
  • the subject matter of the patent not being an invention (e.g. scientific theory as such) or being among the exceptions to patentability (e.g. exploitation contrary to “ordre public” or morality), 
  • insufficient disclosure of the invention in the patent, and/or
  • - the extension of the subject matter beyond the content of the application as filed and/or the content of the original application in the case of a divisional application

The opposition may be directed against the entire patent or only against certain claims. It appears that attacking the description or drawings only is tantamount to attacking the entire patent (Guidelines B, 1.5.).

What are the main steps of the opposition procedure?

Once the opposition has been filed, its admissibility is examined (cf. Article 2/5). At the end of an investigation phase (cf. Article 3/5), which in most cases should end with an oral phase (cf. Article 4/5), the decision must be delivered (cf. Article 5/5). The decision is subject to appeal. 

The following diagram illustrates these steps and indicates which of our articles will detail them.

Who is in charge of the opposition?

If the admissibility examination depends on an administrative officer, the remainder of the opposition is investigated by a referent examining engineer (Guidelines B, 1.7.). This referent examining engineer is assisted by two examining engineers, and possibly a legal expert from the INPI. During the opposition, the prevailing opinion is that of the referent examining engineer.

During the procedure, the INPI observes enforces compliance, including on itself, of the right to be heard (R.613-44-4 CPI). As a fundamental principle of legal proceedings, this guarantees the parties not to be judged without being heard and ensures the preservation of the rights of each party.

Potential role for third parties?

With the exception of cases in which an entitlement action or nullity action against the patent has been filed (cf. Article 3/5), third parties have no place in the opposition proceedings. Third parties may neither intervene nor file observations (Directive B, 1.6.). Intervention is, however, possible in the event of an appeal (cf. Article 5/5).

Nonetheless, the public is informed of the progress of the opposition. As soon as it is filed, the opposition is registered in the National Patent Register (R.613-44-1 CPI). After expiration of the 9-month opposition period, the details of the procedure can be followed on the INPI database (Directives B, 1.8.).

The fundamental principles presented here reflect a desire of lawmakers that the opposition be a simple yet effective procedure. However, this procedure requires careful monitoring of the grant of the patents to which one wishes to oppose in order to avoid missing the opposition deadline. If the deadline has passed, there is an opportunity to bring a nullity action before the Tribunal Judiciaire de Paris (Paris Civil Court of Justice), which requires a demonstration of standing and involves higher costs.

The next article will focus on the filing of the opposition and its admissibility.